(1). Field of the Invention
The present invention relates to an apparatus, used in a step of processing a silicon wafer, for positioning the silicon wafer on the basis of an orientation flat (hereinafter abbreviated to ORIFLA).
(2). Prior Art
When the silicon wafer is carried to a processing device by means of a robot or the like in a step of processing or measuring the silicon wafer, it is required to position the wafer on the basis of the ORIFLA defined as a flat notch formed in the silicon wafer.
For this reason, according to a conventional method, the silicon wafer is rotatably supported; a rubber roller is pushed against the circumference of the wafer; the wafer is turned by rotationally driving the rubber roller; and the wafer is halted just when the rubber roller is separated from the wafer in a position wherein the ORIFLA reaches the rubber roller, thus positioning the silicon wafer.
Inevitably, there is created unevenness in positioning the wafer on the basis of the ORIFLA because of inertial rotation of the silicon wafer, and it is unfeasible to accurately position the wafer. In the conventional positioning apparatus, the stopping position is predetermined, and hence it is unfavourably impossible to arbitrarily position the silicon wafer.